释义 |
Trigonometry Values Pi/11Trigonometric functions of for an integer cannot be expressed in terms of sums, products, and finite rootextractions on real rational numbers because 11 is not a Fermat Prime. This also means that the Undecagon is nota Constructible Polygon.
However, exact expressions involving roots of complex numbers can still be derived using the trigonometric identity  | |  | (1) | Using the identities from Beyer (1987, p. 139),
 | (2) |
 | (3) |
givesNow, let and , then
 | (5) |
This equation is an irreducible Quintic Equation, so an analytic solution involving Finite Rootextractions does not exist. The numerical Roots are , 0.29229, 0.57115, 0.82743, 0.97974. So , , , , . Fromone of Newton's Identities,The trigonometric functions of also obey the identity
 | (9) |
See also Undecagon References
Beyer, W. H. ``Trigonometry.'' CRC Standard Mathematical Tables, 28th ed. Boca Raton, FL: CRC Press, 1987.
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